Method For Simple Retrieval Of Network Access Selection Information

ABSTRACT

The invention relates to a method and system for network access selection comprising an Access Selection Server (ASS) ( 113 ) being arranged in a communication network comprising at least one User Equipment (UE) ( 109 ) and communication nodes. The ASS ( 113 ) collects ( 127 ) access selection information used in the network for the selection of network access for the UE ( 109 ) in a multi-access environment to a Packet Data Network Gateway (PDN GW). The network access enables a traffic bearer ( 116 ) between the UE ( 109 ) and the PDN GW for the traffic flow between an application (AP) ( 115 ) in the UE ( 109 ) via the PDN GW to a first node. The method and system is particularly characterized in that an Access Selection Client (ASC) ( 118 ) arranged in the UE ( 109 ) performs activation of new network accesses and/or selection, modification or deactivation of existing network accesses on the basis of the access selection information in order to enable the traffic flow ( 116 ). The selection/activation/modification/deactivation of the network access is triggered by a socket request sent from the application (AP) to the ASC ( 118 ) for the purpose of establishing means for end-to-end communication the traffic bearer ( 116 ).

TECHNICAL FIELD

The invention relates to a method and system for network accessselection according to the preamble of claims 1 and 38, an AccessSelection Server (ASS) according to the preamble of claim 23 and anAccess Selection Client (ASC) according to the preamble of claim 30.

BACKGROUND

Third generation mobile systems (3G), based on WCDMA (Wideband CodeDivision Multiple Access) radio access technology, are being deployed ona broad scale all around the world. However, as user and operatorrequirements and expectations will continue to evolve a new phase in theproject called 3^(rd) Generation Partnership Project (3GPP) has startedto consider the next major steps in the evolution of the 3G standard.The terminals used in the network are having more functions integratedwhich means that an increasing number of access types such as e.g. LTE(Long Term Evolution), WiMAX (Worldwide Interoperability for MicrowaveAccess) and WLAN (Wireless Local Area Network) and new services such asVoice over IP (VoIP) or IP-TV are added to the terminal. This has theimplication that there is a need for support from the network to guidethe terminal regarding which access to select. The terminal is typicallya mobile telephone and is henceforth in the description and claimscalled a User Equipment, UE.

There is consequently a need for a common core network that can provideaccess for access networks of different kinds and provide all these newservices. One of the main challenges today is therefore to combine alarge number of existing networks to provide a packet based IP corenetwork (SAE-Systems Architecture Evolution is a project studying this)which can provide these various services for the customer. The networksof today are optimized for circuit switched voice telephony. GSM Radio,GERAN and UTRAN are examples of radio access networks where the userconnects to the core network and depending on if they are using GSM,GPRS or 3G they are redirected through the core network.

SAE is a core network that is completely packet switched and provides asolution to the challenge. SAE may interwork together with circuitswitched networks. Handover may also be performed between SAE andcircuit switched networks. The access between the UE and an externalnetwork (Internet, Intranet, Public Switched telephone network (PSTN))is provided by the core network and the access network.

In order to provide a platform for the development of network servicesbased on SIP (Session Initiation Protocol) IMS (IP Multimedia Subsystem)is introduced. IMS contains a standardized network architecture within3GPP for providing multimedia services for the UE. IMS enables a varietyof functions, such as authentication, charging and presence availablefor the developers of different service applications. IMS is highlyinteresting for wireless access of UE comprising a number Of multimediafeatures (voice, video etc). IMS does not depend on type of access andis based on standard IP connectivity and service control architecture byusing Internet-based protocols

Important nodes in the packet based IP core network for data transportare SGSN (Serving GPRS Support Node), GGSN (Gateway GPRS Support Node)and HLR (Home Locations Register). In IMS HLR is a part of HSS (HomeSubscriber Server). SGSN is responsible for the delivery of data packetsfrom and to the UE. Together with the HLR it keeps track of the locationof the UE and carries out security functions and access control.

GGSN acts as gateway between a wireless data network and other networkssuch as internet. It is an anchor point that makes the mobility of theUE possible. Within 3GPP, SAE GW/HA takes over some of the tasks for theGGSN. GGSN converts the GPRS packets coming from the SGSN into theappropriate packet data protocol (PDP) format (i.e. IP) and sends theminto the IP packet data network. In the other direction, PDP addressesof incoming data packets are converted to the GSM address of thedestination user. The readdressed packets are sent to the responsibleSGSN. A PDP context is a data structure that which holds informationabout routing, QoS, billing etc. When a user wants to use a packet basedservice she has to activate a PDP context. GGSN also works as router andfirewall. The HLR/HSS is a central database that keeps details of eachSIM/USIM card, such as the International Mobile Subscriber Identity(IMSI), the telephone number, information on allowed services for thesubscriber, forbidden roaming areas and current location of thesubscriber.

In order to assure the service quality for the end-users in the corenetwork Quality of Service (QoS) is a keyword. Within 3GPP, QoS is apart of the LTE (Long Term Evolution) study aiming for improvements of3G (third generation) technology to ensure long-term competitiveness.Such improvements relate to service provisioning and cost reduction.Better service will be appreciated by customers and consequently resultin higher loyalty and willingness to pay for additional service. Commonfailures that QoS should deal with are packet loss, delay/latency andjitter.

QoS will enable the home operator to control the service rateindividually for each end-user in order to efficiently use the networkresources and provide a more “cost-based” service level. Differentservices need different quality. File transfer protocol (FTP) forinstance is not very sensitive to delays while voice and video are verysensitive to delay and variations. Moreover, different customers expectdifferent quality. Some corporate customers do not accept failure intransmissions and are willing to pay for QoS while others accept somefailure for a lower price. There are also variations between theexpectations for private customers.

Because of QoS, there is a need in the core network to control thecommunication between the UE and the external network. Home operatorsshould be able to provide differentiated services for the customers. Anew architecture within 3GPP for the core network is available for thispurpose. This is called Policy and Charging Control (PCC). It isdisclosed in the technical specification 3GPP TS 23.203 v7.3.0, release7, in which the different functions are specified. The PCC architectureis illustrated in FIG. 1. The functions in FIG. 1 are, according to thisspecification, defined as follows.

The main parts of the PCC architecture according to 3GPP comprises thefollowing entities: an Application Function (AF) 101, a PCRF (Policy andCharging Rules Function) 103, a Subscription Profile Repository (SPR)107 and a PCEF (Policy and Charging Enforcement Function), 105. Theseparts are shown in FIG. 1 and are nodes within the core network. Anentity in a 3GPP system may be realised as node, a part of a node or asdifferent nodes.

The Application Function (AF) 101 is an element offering applications tothe UE and has the possibility to request resource allocation via thePCC in the core network. An application function is a service enablerprovided for the UE which provides a variety of services, such as videocall and web browsing. One example of an application function is aP-CSCF (Proxy-Call Session Control Function). The P-CSCF is a SIP(Session Initiated Protocol) proxy server which is the first point ofcontact for an IMS (IP Multimedia Subsystem) UE. The AF 101 uses an Rxreference point 102 to provide session information to the PCRF (Policyand Charging Rules Function) 103.

The PCRF 103 is a functional element unique for PCC that encompassespolicy control decision and flow based charging control functionalities.The PCRF provides network control regarding the service data flowdetection, gating, QoS (Quality of Service) and flow based charging(except credit management) towards the PCEF (Policy and ChargingEnforcement Function). The PCRF receives session and media relatedinformation from the AF and informs the AF of traffic plane events. A Gxreference point 104 is used for provisioning and removal of PCC rulesfrom the PCRF to the PCEF and the transmission of traffic plane eventsfrom the PCEF to the PCRF.

The PCC contains a number of rules defining how to treat received datapackages. The PCEF shall select a PCC rule for each received packet byevaluating received packets against service data flow filters of PCCrules in the order of the precedence of the PCC rules. The purpose of aPCC rule is to:

-   -   Detect a packet belonging to a service data flow.    -   Identify the type of service that the service data flow        contributes to.    -   Provide applicable charging parameters for a service data flow.    -   Provide policy control for a service data flow.

The PCEF is the functional element that encompasses policy enforcementand flow based charging functionalities. This functional entity islocated at the Gateway GPRS Support Node (GGSN) in the GPRS case. Itprovides control over the user plane traffic handling at the Gateway andits Quality of Service (QoS), and provides service data flow detectionand counting as well as online and offline charging interactions. For aservice data flow that is under policy control the PCEF shall allow theservice data flow to pass through the Gateway 106 if and only if thecorresponding gate is open.

The Subscription Profile Repository function (SPR) 107 contains allsubscriber/subscription related information needed forsubscription-based policies and bearer level charging rules by the PCRF.The. SPR may be combined or integrated with another entity such as theHLR/HSS. The Sp reference point 108 allows the Subscription ProfileRepository (SPR) to provide subscription-based input to the PCRF, allowsthe PCRF to request subscription information related to bearer levelpolicies from the SPR based on subscriber ID and allows the SPR tonotify the PCRF when the subscription information has been changed ifthe PCRF has requested such notifications.

FIG. 2 shows a policy related signalling flow in a PCC system in SAE(System Architecture Evolution) intended to establish a QoS bearer forthe UE in a 3GPP environment. The establishment is network initiated andtriggered by the application's signalling. The UE 109 sends 1 a servicerequest for an application to an AF 112 (a P-CSCF or another type of AF)in the core network. The service could be an IMS service (serviceintended for IMS) or a non-IMS service (service intended for non-IMS).The AF 112 contacts 2 the PCRF 111 and indicates the type of servicerequested and its requirements on the communication quality. AF alsoprovides service data flow templates/traffic flow templates,SDFT(s)/TFT(s) (protocol identifiers, ports and addresses) for theapplication's media flow. (In terms of informational content SDTF(s) andTFT(s) are equivalent.

For simplicity only the term TFT will be used in the remainder of thetext. It should be interpreted as either TFT or SDTF, whichever is themost appropriate in the present context. With this input data togetherwith applicable policies the PCRF assigns 3 an appropriate QoS to themedia flow. The QoS indication is not tied to any particular bearer oraccess type but a generic indication.

The PCRF 111 sends 4 the selected QoS indication (and chargingindications) together with the TFT(s) to the SAE GW/HA 110 (PCEF) andrequests it to establish 5 a bearer that matches the indicated QoS tothe UE 109. If the currently used access is of a type that supports theconcept of network initiated bearer establishment, such as LTE or 3G,the SAE GW/HA establishes the requested bearer. Acknowledgements aresent 6,7 all the way back to the AF 112, which concludes 8 the servicesignalling towards the UE 109. Then the actual media flow is started 9.

With the increasing number of access types added to the UE's there is aneed for support from the core network to guide the UE regarding whichaccess to select in order to provide the communication link with the QoSthat the subscriber has paid for: Other aspects that potentially mayimpact the access selection are e.g. the user's preferences, theoperator's policies, cost of network usage, current load conditions,ensuring efficient use of the network resources and type of application.Such access types are e.g. LTE (Long Term Evolution), WiMAX (WorldwideInteroperability for Microwave Access) and WLAN (Wireless Local AreaNetwork). Objectives for the operator are to differentiate the QoS fordifferent users by operating with e.g. Olympic subscriptions (gold,silver, bronze), time varying policies/tariffs and location-basedpolicies. Other objectives are service dependent (best possible accessper service) and load management (static or dynamic). Objectives for theuser are automated access selection (less complex), automated networkdiscovery, tariff-dependent access priority, defining preferred networksand service-dependent priorities.

Within the PCC architecture there is provided a framework for a multiaccess steering control. The steering control is based on thedistributed approach with an access selection (AS) client (ASC) in theUE and an access selection server (ASS) in the core network. Both theclient and the node collect information that is relevant for accessselection decisions. The ASS gathers information from the network aboutload status etc. and information from the UE about all accessesavailable. This information is used by the ASS in the steering control.The ASS sends control messages based on the stored information to theASC, thereby enabling control of multiple UE-accesses. The ASS providesthe UE AS client with information for access selection and suggests asuitable access. The final decision on access selection is performed bythe ASC.

In a first approach within the access steering control the ASC isrealized as a shim layer between the application layer and the transportlayer in the UE's (IP) protocol stack. The ASC receives indications fromthe application layer (i.e. from an application running in the UE) aboutthe service request and which applications the UE wants to use via asocket request. This information, together with policies and otherrelevant information, such as available accesses and possible networkload, is then used as input data to the access selection decision. Ifthe current access is selected by the ASC a socket is established andthe application's communication can begin. If another access is selecteda Mobile IP (MIP) handover to the selected access network is performedor the interface towards the selected address is configured in parallelwith the old address. MIP is a protocol that allows mobile device usersto move from one network to another while maintaining a permanent IPaddress.

According to the first approach the multi access steering controlidentifies the application (service needed) from the port numbers sentwith the socket request in order to trigger the access selectiondecision to infer with the application's requirements of thecommunication quality. The socket request is in the form of socketconnect( ) calls for TCP (Transmission Control Protocol) and sendmsg( )and sendto( ) calls for UDP (User Datagram Protocol). The steeringcontrol consequently identifies capacity and properties of the bearerneeded for a particular application in order for the application to runproperly. For instance streaming video and voice needs a higher capacitywhile SMS needs a lower capacity.

TCP (or UDP) ports refer to specific application protocols or uses.Applications use particular application protocols such as IMAP foremail, POP3 for receiving emails and HTTP for web browsing. During asocket request the concerned application in the computer or UE sends theport number for the application it wants to use and requests for atransport end-point which can be bound to a socket address for packetdata transfer from and to the computer or UE in the transport layerthrough a communication connection. A socket consists of a combinationof port numbers and IP addresses and an implicit or explicit indicationof the transport protocol. In particular it is composed of a transportprotocol indication (e.g. TCP or UDP, often implemented implicitly asdifferent types of sockets), the source IP address and port and thedestination (remote end-point in a packet-based network) IP address andport.

In a second approach within the access steering control the focus is onthe interaction between the access selection functionality and the SAEpolicy management. This approach is described in a patent applicationfiled on the same day. The ASS is there involved in the IMS signallingin order to insert the access selection in the session setup procedure.In this approach, illustrated in FIG. 3, an initial IMS sessionsignalling 1 is performed. The AF 112 (the P-CSCF) the contacts 2 theASS 113 and indicates the type of application that is being establishedbased on CSI (Communication Service Identifier) and SDP (SessionDescription Protocol) information. Based on this and other relevantinput data (load status, available accesses etc) the entity 113 selects3 an access for the application and informs 4, 5 the UE 109 and the AF112 (the P-CSCF) of its decision. The IMS session signalling is thecontinued 5 with bearer establishment via the PCRF 111 and the SAE GW/HA(PCEF) and concluding SIP signalling. If another than the current accesswas selected, the originating UE sends a SIP (Session InitiationProtocol) reinvite message to the other end reflecting the new access.

It has been apparent that the UE-based method for multi access steeringcontrol, with an AS server (ASS) introduced in the core network, is apragmatic and simple approach which has a lot of benefits in theprovision of appropriate access selection decisions. However, there is aneed for a sufficient identification of the application during thesocket request as proposed in the first approach. Using port numbers ispromising but it however needs some improvements.

The reason is that some applications involve preceding servicesignalling (socket request) and use separate (TCP/UDP) connections forsignalling and media (data) flows (in transport layer), e.g. SIP-based(Session Initiation Protocol) applications. The port numbers for themedia flow (following the service signalling) may be selected more orless arbitrary during the preceding service signalling.

For such applications the port numbers will not be sufficient toidentify the type of media flow (type of application) and itsrequirement in terms of bearer capacity and QoS. The multi accesssteering control will face a socket request with unrecognized portnumbers indicated. In this situation it cannot make an intelligentaccess steering decision, because it lacks the required informationabout the properties and requirement of the application. It may be thatthe multi access steering control uses other means than port numbers forthe identification of an application such as finding out the owner ofthe process sending the socket call. However, also in such situationsthe multi access steering control may face a socket request with anunrecognized source application or that the type of media flow to be setup is unknown.

Furthermore, the second approach within multi access steering controlfocusing on the interaction between the ASS and the SAE policymanagement also needs some improvements. One reason is that it iscompletely geared towards IMS-based services. Its integration into theIMS signalling does not take non-IMS based services into account.Another reason is the fact that IMS signalling from the UE is affectedwhich implies a non-trivial interaction between the multi accesssteering control and the IMS application. While such interaction couldprovide advantages, it is complex and may be much harder to bring fromconcept to deployment than a solution that leaves the applicationunaffected. It is an advantage if the application does not have to beadapted for enabling access selection functionality.

SUMMARY

The invention intends to remove the above mentioned deficiencies ofprior art solutions and to find an improved solution to multi accesssteering control for a User Equipment (UE) in a communication network.This is accomplished by providing:

The invention relates to a method and system for network accessselection comprising an Access Selection Server (ASS) being arranged ina communication network comprising at least one User Equipment (UE) andcommunication nodes. The ASS collects access selection information usedin the network for the selection of network access for the UE in amulti-access environment to a Packet Data Network Gateway (PDN GW). Thenetwork access enables a traffic bearer (116) between the UE and the PDNGW for the traffic flow between an application (AP) (115) in the UE(109) via the PDN GW to a first node.

The method and system is particularly characterized in that an AccessSelection Client (ASC) arranged in the UE performs activation of newnetwork accesses and/or selection, modification or deactivation ofexisting network accesses on the basis of the access selectioninformation in order to enable the traffic flow. Theselection/activation/modification/deactivation of the network access istriggered by a socket request sent from the application (AP) to the ASCfor the purpose of establishing means for end-to-end communication thetraffic bearer.

The invention further relates to an Access Selection Server (ASS) beingarranged in a communication network comprising at least one UserEquipment (UE) (109) and communication nodes. The ASS is adapted forcollecting access selection information used in the network for theselection of network access for the UE in a multi-access environment toa Packet Data Network Gateway (PDN GW). The network access enables atraffic bearer between the UE and the PDN GW for the traffic flowbetween an application (AP) in the UE via the PDN GW to a first node.The ASS is particularly characterized in that it is further adapted forsending the access selection information to the UE (109).

The invention also relates to an Access Selection Client (ASC) beingarranged in a communication network comprising at least one UserEquipment (UE) (109) and communication nodes. The access selectioninformation is used in the network for the selection of network accessfor the UE in a multi-access environment to a Packet Data NetworkGateway (PDN GW). The network access enables a traffic bearer betweenthe UE and the PDN GW for the traffic flow between an application (AP)in the UE via the PDN GW to a first node. The ASC is particularlycharacterized in that it is arranged in the UE and adapted forperforming activation of new network accesses and/or selection,modification or deactivation of existing network accesses on the basisof the access selection information in order to enable the traffic flow.The selection/activation/modification/deactivation of the network accessis triggered by a socket request sent from the application (AP) to theASC for the purpose of establishing means for end-to-end communicationincluding the traffic bearer.

One advantage of the present invention is that it provides a simplemechanism for providing relevant input data for multi access steeringcontrol concerning applications, which cannot be identified through theport numbers or by finding out the process owner of the socket calland/or whose requirements for data transmission are unknown. A furtheradvantage is that the invention is both applicable for IMS-based and nonIMS-based services. Moreover, the invention does not interfere withservice related signalling such as SIP signalling. Another advantage isthat it leaves the applications unaffected. Moreover, the invention doesnot interfere with the regular SAE policy machinery in any other waythan for information retrieval. Finally, the invention can be used alsofor known applications for which insufficient information is availablein the terminal.

Further advantages are achieved by implementing one or several of thefeatures of the dependent claims which will be explained below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Schematically shows Policy and Charging Control (PCC) accordingto prior art.

FIG. 2 Schematically shows a signalling diagram for policy relatedsignalling in SAE.

FIG. 3 Schematically shows a signalling diagram with the interactionbetween the multi access steering control and the SAE policy relatedsignalling for IMS based services according to one approach to multiaccess steering control which is disclosed in another pendingapplication.

FIG. 4 Schematically shows the Access Selection Control according to thepresent invention.

FIG. 5 Schematically shows the method performed by the Access SelectionServer (ASS) and the Access Selection Client (ASC) for collecting accessselection information used in the ASC decision of network access.

FIG. 6 Schematically shows a signalling diagram for service signallingfor the purpose of bearer establishment.

FIG. 7 Schematically shows a signalling diagram for an embodiment wherethe sending of access selection information is made independently of anyrequest from the Access Selection Client.

FIG. 8 Schematically shows a signalling diagram for an embodiment wherethe sending of access selection information is made after a request fromthe Access Selection Client.

DETAILED DESCRIPTION

The invention will now be described in detail with reference toembodiments described in the detailed description and shown in thedrawings. FIGS. 1, 2 and 3 have already been described in relation toBackground above.

In FIG. 4 an Access selection Server (ASS) 113 is shown being part of acommunication network. The network further comprises a User Equipment(UE) 109 and communication nodes. The term “node” is herein used in ageneral sense. It should be understood that different nodes may beintegrated into a single node and that the functionsrepresented/employed by a node could also be realized as separate nodes.

The nodes shown in FIG. 4 are the ones relevant in relation to thepresent invention. One of these nodes is an Application Function 112,which is an element that offers applications (AP) 115 in the UE thepossibility to request 122 service and resource allocation in thecommunication network, the resource being a traffic bearer 116 fortraffic flow in the traffic plane from the application to the networkvia a Packet Data Network Gateway (PDN GW) (not shown). The trafficbearer will be described later. The PDN-GW could be a SystemsArchitecture Evolution (SAE) Gateway (GW)/Home Agent (HA) in a SAEnetwork in a 3GPP domain. The AF could comprise a Proxy-Call SessionControl Function (P-CSCF) for the purpose of IP Multimedia Subsystem(IMS) services. The AF communicates with the UE through defaultsignalling bearers for the purpose of service signalling.

Another one of these nodes is the Policy and Charging Rules Function(PCRF) 111 which is an element that encompasses policy control decisionsand flow based charging control function through rules. PCRF providesnetwork control 123 regarding the traffic flow 116 detection, gating,Quality of Service (QoS) and flow based charging. PCRF communicates 124with the AF112 and receives session and media related information fromthe AF using a reference point Rx 102 (see FIG. 1). The rules for thenetwork control of traffic flow defines how to treat received datapackages, filter that IP flows are transported in the correct trafficbearer, identify the service the service data flow contributes to andprovide policy control for a service data flow. PCRF control the trafficflow in the traffic plane through the PDN GW via a Policy and ChargingEnforcement (PCEF) 105 (see FIG. 1) in the PDN GW.

The ASS 113 is an element that is able to gather information from thenetwork about load status etc. and information from the UE about allnetwork accesses available. This information in some approaches is usedby the ASS in the steering control wherein the ASS sends controlmessages 117 based on the stored information to an AS Client (ASC) 118arranged in the UE, thereby enabling control of multiple UE-accesses.The ASS provides 117 the ASC with information for network accessselection and suggests a suitable access. The final decision on accessselection is performed by the ASC. The ASS and ASC communicate throughdefault signalling bearers for the purpose of service signalling117,119.

In the following specification the ASS 113 and the ASC 118, both beingpart of a system, are adapted for performing the described signallingflow for the network access selection as also disclosed in the claims.In the embodiment according to the present invention the ASS is arrangedin the communication network with at least one User Equipment (UE) 109and the communication nodes.

FIG. 5 schematically illustrates the method performed by the ASS 113 andASC 118 for collecting access selection information used in the ASCdecision of network access. The method gives the advantage of a simplemechanism for providing relevant input data for multi access steeringcontrol by the ASC concerning applications, which cannot be identifiedby the ASC through the traffic flow port numbers or by finding out theprocess owner of the socket call and/or whose requirements for datatransmission are unknown. Moreover, the invention is both applicable forIMS-based and non IMS-based services and does not interfere with servicerelated signalling such as SIP signalling. Another advantage is that isleaves the applications unaffected. Moreover, the invention does notinterfere with the regular SAE policy machinery in any other way thanfor information retrieval. Finally, the invention can be used also forknown applications for which insufficient information is available inthe terminal.

With reference to FIG. 5 the ASS 113 collects 127 access selectioninformation which is used in the network for the selection of networkaccess for the UE in a multi-access environment to a Packet Data NetworkGateway (PDN GW). A multi-access environment is where the UE is able toconnect to different access technologies, e.g. Radio Access Technologies(RAT) such as WLAN, 3G and WiMAX. The characteristics of the accessselection information will be described further below. The networkaccess will enable a traffic bearer between the UE and the PDN GW forthe traffic flow in the traffic plane between the application (AP) 115in the UE via the PDN GW to a first node. The first node is a node whichthe application communicates with in an end-to-end communication.

The ASC being arranged in the UE performs 129 activation of new networkaccesses and/or selection, modification or deactivation of existingnetwork accesses on the basis of the access selection information inorder to enable the traffic flow. The characteristics of the accessselection information will be described later. The network access mayalready be prepared, for instance if a default access used for theservice signalling (see below) is selected. Consequently, an existingnetwork access could simply be selected.

The selection/activation/modification/deactivation of the network accessis triggered by a socket request sent 137 from an application (AP) 115in the UE 109 to the ASC 118 for the purpose of establishing means forend-to-end communication including the traffic bearer. Means forend-to-end communication is for instance a communication channel or atransport layer connection, with another node. This means that thesocket request is preceded by a service signalling where the applicationasks for a network permission to establish the bearer.

The service signalling from the application will now be described withreference to FIG. 6. The service signalling is performed for the purposeof requesting the traffic bearer. The application wants to establish atraffic bearer and requests permission from the network to establishsuch a bearer.

During the service signalling the AP 115 contacts 130 an ApplicationFunction (AF) 112 or a second node via the AF, providing port numbers,wherein the AF 112 or the second node together with the AP 115 agreesupon the transport protocol, IP addresses and port numbers for thetraffic flow, wherein the AF becomes aware of the transport protocol, IPaddresses and port numbers. Irrespective of whether the AP forms thisagreement with the AF or with the second node via the AF, the signallingprocedure makes the AF aware of the transport protocol, the IP addressesand port numbers that have been agreed from the traffic flow.

The AF 112 further contacts the PCRF 111 via the communication link 124,and provides 132 the transport protocol, the addresses and port numbersin the form of Traffic Flow template (TFT) parameters together withinformation about the properties and communication requirements of theservice requested. This means that AF, or the second node reachable viathe AF, together with the AP 115 has agreed upon the ports and the IPaddresses of the requested traffic bearer for the traffic flow.

Traffic Flow Template parameters are used by the PDN Gateway to filterand identify traffic flows and to ensure that traffic flow for aparticular application does not have to share bearer with any othertraffic flow. For simplicity only the term TFT will be used in theremainder of the text. It should be interpreted as either TFT or SDTF,whichever is the most appropriate in the present context.

When the PCRF 111 receives the information it assigns 133 Quality ofService (QoS) information to the TFT defining the properties of therequested traffic bearer. This means that the bearer for the trafficflow of the application, which the application service signallingrequests, is assigned to a certain Quality of Service, for instance interms of data transmitting capacity.

The access selection information comprises the QoS on which basis theselection/activation/modification/deactivation of the network access isperformed 143 (see FIG. 8) by the ASC. The QoS information is assigned133 by the PCRF 111 to the Traffic Flow Template (TFT) parametersreceived from the AF 112.

There are two options regarding from where the bearer is established.For both options, the PCRF informs the PDN GW that a traffic bearer witha certain QoS is needed for a traffic flow matching certain TFTparameters. This is done by sending the QoS information and the TFTparameters to the PDN GW. In most access networks, the first option, thetraffic bearer is set up from the UE 109 (denoted UE initiated bearerestablishment). With such an option the PDN GW will wait for the bearerto be established by the UE. The AP 115 triggers the UE to establish thetraffic bearer by sending a socket request to the transport layer in theIP stack (although from the AP's point of view the socket request isprimarily a way to establish means for end-to-end communication, i.e. acommunication channel or a transport layer connection, with anothernode, e.g. an AF or another type of peer node). With the ASC 118, thesocket request is firstly received by the ASC, which firstly makes thenetwork access selection and then forwards the socket request to thetransport layer.

In pure 3GPP access networks (3G-UTRAN and LTE), the second option, thetraffic bearer between the AP 115 in the UE 109 and the PDN GW isestablished by the PDN GW (denoted network initiated bearerestablishment) In the second option the PDN GW sends 128 the accessselection information to the UE. The establishment is triggered by thePCRF 111 delivering QoS information and TFT parameters to the PDN GW.The PDN GW initiates the establishment and signals the QoS informationand the TFT parameters to the UE.

In a first embodiment, the QoS information being access selectioninformation is sent by the network independently of any request from theASC 118. service signalling preceding the socket request results in theassignment 133 of QoS information to the application's traffic flow. Theassignment in turn triggers the sending 134 (see FIG. 7) of the QoSinformation and the TFT parameters from the PCRF 111 to the ASS 113.

Within the first embodiment relating to a proactive information transferwithout any request from the ASC 118, the ASS 113 decides which accessto be selected/activated/modified/deactivated 144 (dotted in FIG. 7since this in one option) on the basis of the QoS information received134. The ASS then sends information about its decision together with theTFT parameters and optionally the QoS information to the ASC 118, sothat the ASC can execute the decision.

The ASC uses the received TFT parameters to match the received accessselection decision with the socket request (which has socket parametersmatching the TFT parameters) to which the access selection decisionshould be applied. If the first option for bearer establishment (UEinitiated) is used the UE then selects/activates/modifies/deactivatesthe traffic bearer in accordance with the received decision. If thesecond option for traffic bearer establishment (network initiated) isused, then the ASC checks whether the selected access is the one overwhich the network initiated traffic bearer is established. If it is,then this network initiated traffic bearer is used for the traffic flow.If the selected access is another then the one which the networkinitiated traffic bearer is established, then the ASC initiates ahandover to the selected network access.

As an alternative within the first embodiment the ASS 113 forwards 136the received QoS information and TFT parameters to the ASC 118 whenreceiving it from the PCRF 111. The ASC then uses the QoS information asinput data to an access selection decision. As above, the ASC uses theTFT parameters to match the received access selection decision with thesocket request (which has socket parameters matching the TFT parameters)to which the access selection decision should be applied. As in thefirst alternative, if the first option for traffic bearer establishment(UE initiated) is used, the UE selects/activates/modifies/deactivatesthe traffic bearer in accordance with the access selection decision.

Again as in the first alternative, if the second option for trafficbearer establishment (network initiated) is used, then the ASC checkswhether the selected access is the one over which the network initiatedtraffic bearer is established. If it is, then this network initiatedtraffic bearer is used for the traffic flow. If the selected access isanother then the one which the network initiated traffic bearer isestablished, then the ASC initiates a handover to the selected networkaccess.

The main aspect of the present invention is to provide the QoSinformation to the ASC, which will indicate the network access needs forthe traffic bearer and helps the ASC in its access selection decision(However, according to one above described option in the firstembodiment, an access selection decision based on the QoS information issent to the ASC instead of the QoS information). According to the firstand the second embodiments, the network will proactively send this QoSinformation (or access selection decision) to the ASC, triggered by theservice signalling. According to the third embodiment (will be describedlater) the ASC will request the QoS information from the network whenreceiving a socket request from the AP 115.

A second embodiment of the invention can be used only when the secondoption for traffic bearer establishment (network initiated) is used. Inthis second embodiment, during the bearer establishment signalling thePDN GW informs the UE which QoS that is supported (which QoS the GW willaccept for the traffic bearer) and for which media flow the bearer isintended by sending the QoS information and the TFT parameters to theUE. When the socket request is made by the AP, a traffic bearer isalready established with TFT parameters that match the socket parameters(protocol indication, port numbers and IP addresses) and which bearercan carry the traffic flow supplied through the socket for theparticular service.

In the second embodiment a module in the UE 109 that handles thesignalling with the PDN GW contacts the ASC 118 (a different module inthe UE) and informs which QoS that belongs to the TFT parametersreceived by the PDN GW. The ASC can store this information and wait forthe socket request from the AP 115 with the socket parameters thatmatches these TFT parameters. When the socket request arrives, the ASCknows the QoS assigned by the PCRF 111 for the traffic flow that thesocket request relates to. It can use this information as input data forthe access selection decision. If the network access selected is thepresent 3GPP access, the bearer established by the PDN GW is used. Ifanother access is selected a handover is performed.

It may happen that the socket request arrives before the PDN GW hasestablished the traffic bearer. If so, the ASC, when it has received thesocket request, has to wait for the TFT parameters and the QoSinformation from the UE module handling the 3GPP signalling with the PDNGW, before it can perform its access selection.

In a third embodiment, mainly QoS information, which is access selectioninformation, is sent 142 from the ASS to the ASC when requested 138 bythe ASC 118 via the ASS 113. The ASC does not have to send the TFTparameters, since in this embodiment the ASC already knows them from thesocket parameters in the socket request. This embodiment will bedescribed with reference to FIGS. 4 and 8. In the embodiment the sending142 of the QoS information to the ASC is indirectly initiated by asocket request sent 137 to the ASC from the application (AP) 115 for thepurpose of establishing 143 means for end-to-end communication,including the network access for the traffic flow in the traffic plane.This socket request includes the socket parameters including protocolindicator (explicitly or implicitly as type of socket), IP addresses andthe traffic flow port numbers.

In a first alternative according to the third embodiment, the ASC 118 isunable to deduce from the traffic flow port numbers the properties andrequirements of the traffic flow the socket is intended for, because theapplication has included port numbers in the socket request which areunknown to the ASC, i.e. which the ASC cannot associate with a certainapplication or type of traffic flow. The fact that the port numbers arenot identified triggers the ASC to send the request 138 to the ASS.

In a second alternative according to the third embodiment the ASC canidentify the application requesting a socket from the port numbers, butthis identification is not enough to (sufficiently well) infer theapplication's communication requirements, e.g. because the media flow'srequirements depend on negotiations in the preceding service signaling.Also in these cases the AS client can use the method according to thefirst alternative to retrieve relevant input data to a well-foundedaccess selection decision.

The ASC 118 sends 138 a request including the socket parameters to theASS 113, requesting the ASS to send back 142 the QoS informationcorresponding to the sent traffic flow socket parameters. Thiscommunication is illustrated as arrows 117/119 in FIG. 4.

The ASS further sends 142 the QoS information to the ASC as requestedwhen collected from the PCRF 111, as described later. As an alternative,in order to increase the support from the ASS, could be that the ASserver converts the received QoS information into data of a form that ismore suitable as input data to the access selection algorithm beforetransferring the data to the ASC. This may be very useful, since the QoSinformation delivered from the PCRF 111 may have operator-specificinterpretations. According to this alternative, the ASS consequentlyconverts the QoS information into data of a different form beforesending it to the ASC as requested.

Upon receiving said request from the ASC, the ASS 113 sends 139 ansecond request, including the received parameters to the PCRF 111requesting the PCRF to send back 141 the QoS information correspondingto the parameters. The PCRF further sends 141 the QoS information to theASS as requested when the received parameters have been compared 140with its stored TFT parameters, previously sent 132 (see FIG. 6) to thePCRF by the AF 112 during the service signalling and QoS assignmentprocedure, to provide 141 the requested QoS information to the ASS.

Within the third embodiment the ASC 118 performs a default networkaccess decision when the socket request is received from theapplication. When the QoS information then is received from the ASS 113a handover is made to the access selected, if the selected access isanother than the one selected by the default access decision.Alternatively, the ASC retrieves (FIG. 8) the QoS Information beforeaccepting the socket request. According to this alternative, the ASCdoes not make a default access selection and accept the socket requestbefore requesting additional information from the ASS 113. Not beforethe ASS has returned the QoS information does the ASC run the accessselection algorithm and accept the socket request. This alternativevariation decreases the complexity to a certain extent, but thedisadvantage is that the application will experience a longer delaybefore its communication can commence.

Within one alternative of the first embodiment, see FIG. 7, the ASS 113performs the decision 144 of which network access to beselected/activated/modified/deactivated on the basis of the QoSinformation received 134 from the PCRF. The ASC then executes the ASS'sdecision when it has identified the traffic flow to which the decisionshould be applied by comparing the TFT parameters received 136 from theASS with the socket parameters received 134/135B/136 by the UE 109 andsocket parameters sent to the ASC 118 from the application 115 for thepurpose of establishing the traffic flow over the network access. Whenthe parameters received by the UE from the ASS correspond to theparameters of the application theselection/activation/modification/deactivation is performed 143 inaccordance with the decision of the ASS.

Within the other alternative of the first embodiment, the ASS does notperform any decision by itself, but instead proactively forwards 136(possibly after modification to a more suitable form) to the UE the QoSinformation and TFT parameters received 134 from the PCRF. Also in thesecond embodiment are the QoS information and the TFT parametersproactively sent to the UE, although in the second embodiment they aresent from the PDN GW instead of from the ASS. In both cases the factthat the ASC 118 can collect parameters and QoS received by the UE,about the assignment of the bearer for the traffic flow, means that theASC is able to make its access selection decision. The informationprovided helps the ASC to identify the characteristics and/orrequirements/needs of the concerned traffic flow by reading the QoSassigned to the application's media flow.

The advantage of the first and the second embodiments are that the QoSinformation (or ready-made access selection decision as in onealternative of the first embodiment) is brought quicker to the ASC 118and it may even arrive before the socket request from the applicationarrives. With the quicker access selection decisions that this methodprovides, it would be possible to wait for a well-based decision insteadof letting the application start communicating over a default access.

Within the third embodiment the ASC 118 performs 143 theselection/activation/modification/deactivation of a network accesses onthe basis of the QoS information received 142 by the UE from the ASS113, see FIG. 8. The ASC uses the QoS information in the accessselection process by rerunning its access selection algorithm (orrunning it for the first time if it has not run it yet) with the QoSinformation as additional input data providing information about theapplication's requirements. The fact that the ASC 118 can requestinformation from the ASS, which in turn retrieves it from the PCRF aboutthe QoS assigned to the bearer for the concerned traffic flow means thatthe ASC is able to make its access selection decision. The informationprovided helps the ASC to identify the characteristics and/orrequirements/needs of the concerned traffic flow by reading the QoSassigned to the application's traffic flow.

When the access selection decision is made by the ASC 115 it performs ahandover between two different network accesses as a part/result of theselection/activation/modification/deactivation. This is if a differentaccess is selected than the default access.

As an option the ASC 118 is able to store the received 136,142 QoSinformation, so that it is available e.g. when a subsequent message withthe same socket parameters is to be sent from a UDP application.

As an option the ASS 113 further subscribes to changes in QoSinformation from the PCRF 111 in order to cover application propertychanges, with subsequent consequent QoS changes that may occur withoutchanging the socket parameters. I.e. it could ask the PCRF to send anindication if the QoS information for the concerned protocol indicator,addresses and traffic flow port numbers (i.e. for the matching TFTparameter) changes. The ASS 113 when receiving QoS information changesfrom the PCRF 111 as a result of the subscription to changes in the QoSinformation further informs the ASC 118 of these QoS informationchanges. The ASC would rerun the access selection algorithm and takeappropriate actions if needed. Such a subscription to QoS informationchanges would cover application property changes (controlled via servicesignaling between the UE and the AF), or between the UE and another nodevia the AF with subsequent consequent QoS changes, that may occurwithout changing the socket parameters (in terms of protocol indicator,addresses and port numbers).

It will also be appreciated by the person skilled in the art thatvarious modifications may be made to the above-described embodimentswithout departing from the scope of the present invention.

1. A method for network access selection comprising an Access SelectionServer (ASS) (113) being arranged in a communication network comprisingat least one User Equipment (UE) (109) and communication nodes, the ASS(113) collecting (127,141) access selection information used in thenetwork for the selection of network access for the UE (109) in amulti-access environment to a Packet Data Network Gateway (PDN GW), thenetwork access enabling a traffic bearer (116) between the UE and thePDN GW for the traffic flow between an application (AP) (115) in the UE(109) via the PDN GW to a first node, characterized in that an AccessSelection Client (ASC) (118) being arranged in the UE (109) performs(129,143) activation of new network accesses and/or selection,modification or deactivation of existing network accesses on the basisof the access selection information in order to enable the traffic flow(116), the selection/activation/modification/deactivation (143,144) ofthe network access being triggered by a socket request sent (137) fromthe application (AP) to the ASC (118) for the purpose of establishingmeans for end-to-end communication including the traffic bearer (116).2. Method according to claim 1 wherein a service signalling is performedfor the purpose of requesting the traffic bearer, the service signallingcomprising the steps of: the AP (115) contacting (130) an ApplicationFunction (AF) (112) or a second node via the AF (112), providing portnumbers, wherein the AF (112) or the second node together with the AP(115) agrees upon the IP addresses and port numbers for the trafficflow, wherein the AF becomes aware of the transport protocol, IPaddresses and port numbers, the AF (112) further contacting a Policy andCharging Rules Function (PCRF) (111) and provides (132) the transportprotocol, the addresses and port numbers in the form of Traffic Flowtemplate (TFT) parameters together with information about the propertiesand communication requirements of the service requested, the PCRF (111)assigning (133) a Quality of Service (QoS) information to the TFTparameters, the assignment (133) defining the properties of therequested traffic bearer.
 3. Method according to claim 2 wherein theaccess selection information (109) comprises the Quality of Service(QoS) information on which basis theselection/activation/modification/deactivation of the network access isperformed (143).
 4. Method according to any of the claims 2-3 whereinthe ASS (113) sends (128,136,142) the access selection information tothe UE (109).
 5. Method according to any of the claims 2-4 wherein theassignment (133) of QoS information by the PCRF (111) triggers a sending(134) of the QoS information and the TFT parameters from the PCRF (111)to the ASS (113).
 6. Method according to claim 5 wherein the ASS (113)decides which access to be selected/activated/modified/deactivated (144)on the basis of the QoS information received (134), information aboutthe network access together with QoS information and TFT then being sent(136) to the ASC (118).
 7. Method according to any of the claims 5-6wherein the ASS (113) forwards (136) the received QoS information andTFT parameters to the ASC (118) when received from the PCRF (111). 8.Method according to any of the claims 2-3 wherein the PDN GW sends(128,136,142) the access selection information to the UE (109). 9.Method according to claim 8 wherein a delivering of QoS information andTFT parameters to the PDN GW by the PCRF (111) triggers an establishmentof the traffic bearer (116) by the steps of: the PDN GW initiating theestablishment of the traffic bearer (116) to the UE (109). the PDN GWsignalling the QoS information and the TFT parameters to the UE (109).10. Method according to any of the claims 2-4 wherein a socket requestsent (137) to the ASC (118) from the application (AP) (115) for thepurpose of establishing means for end-to-end communication, includingthe network access indirectly initiates a sending (142) of the QoSinformation to the UE (109), the socket request comprising the socketparameters including protocol indicators, IP addresses and the trafficflow port numbers.
 11. Method according to claim 10 wherein the ASC(118) is unable to deduce from the traffic flow port numbers theproperties and requirements of the traffic flow the socket is intendedfor.
 12. Method according to any of the claims 10-11 wherein the ASC(118) sends (138) a request including the socket parameters to the ASS(113), requesting the ASS (113) to send back (142) the QoS informationcorresponding to the sent traffic flow socket parameters, the ASS (113)further sending (142) the QoS information to the ASC (118) as requested.13. Method according to claim 12 wherein the ASS (113) converts the QoSinformation into data of a different form before sending (142) it to theASC (118) as requested.
 14. Method (113) according to any of the claims12-13 wherein the ASS (113) upon receiving the request from the ASC(118) sends (139) a second request including the received parameters tothe PCRF (111) requesting the PCRF to send back (141) the QoSinformation corresponding to the parameters, the PCRF (111) furthersending (141) the QoS information to the ASS (113) as requested. 15.Method (113) according to claim 14 wherein the PCRF (111) compares (140)the received parameters with its stored TFT parameters to provide (141)the requested QoS information to the ASS (113).
 16. Method according toany of the claims 10-15 wherein the ASC (118) performs a default networkaccess decision when the socket request is received.
 17. Methodaccording to any of the claims 1-9 wherein the ASS (113) performs (143)the decision of which network access to beselected/activated/modified/deactivated on the basis of the QoSinformation received 134 from the PCRF (111), the ASC executing the ASSdecision when it has identified the traffic flow to which the decisionshould be applied by comparison between the TFT parameters received(136) by the UE (109) and socket parameters sent to the ASC from theapplication (AP) (115) for the purpose of establishing the traffic flowover the network access, wherein when the parameters received (142) bythe UE (109) corresponds to the parameters of the application (AP) (115)the selection/activation/modification/deactivation is performed (143) inaccordance with the decision of the ASS.
 18. Method according to any ofthe claims 10-16 wherein the ASC (118) performs (143) theselection/activation/modification/deactivation of a network accesses onthe basis of the QoS information received (142) by the UE.
 19. Methodaccording to any of the claims 17-18 wherein the ASC (118) performs ahandover between two different network accesses as a part/result of theselection/activation/modification/deactivation.
 20. Method according toany of the claims 2-19 wherein the ASC (118) stores the received(136,142) QoS information.
 21. Method according to any of the claims2-20 wherein the ASS (113) subscribes to changes in QoS information fromthe PCRF (111).
 22. Method according to claim 21 wherein the ASS (113)when receiving QoS information changes from the PCRF (111) as a resultof the subscription to changes in the QoS information further informsthe ASC (118) of these QoS information changes.
 23. Access SelectionServer (113) being arranged in a communication network comprising atleast one User Equipment (UE) (109) and communication nodes, the ASS(113) being adapted for collecting (127,141) access selectioninformation used in the network for the selection of network access forthe UE (109) in a multi-access environment to a Packet Data NetworkGateway (PDN GW), the network access enabling a traffic bearer (116)between the UE and the PDN GW for the traffic flow between anapplication (AP) (115) in the UE (109) via the PDN GW to a first node,characterized in that the ASS (113) further being adapted for sending(128,136,142) the access selection information to the UE (109).
 24. ASS(113) according to 23 wherein the ASS (113) further being adapted forreceiving QoS information and the TFT parameters sent (134) by the PCRF(111).
 25. ASS (113) according to claim 24 wherein the ASS (113) isfurther adapted for deciding which access to beselected/activated/modified/deactivated (144) on the basis of QoSinformation received (134,135), the ASS (113) further being adapted forthen sending (136) the information about the network access togetherwith QoS information and TFT to the ASC (118).
 26. ASS (113) accordingto any of the claims 24-25 wherein the ASS (113) is further adapted forforwarding (136) the received QoS information and TFT parameters to anASC (118) in the UE when received from the PCRF (111).
 27. ASS (113)according to claim 23 wherein the ASS is further adapted for uponreceiving a request from an Access Selection Client (ASC) (118) in theUE sending (139) an second request including the received parameters ofthe request to a PCRF (111) requesting the PCRF to send back (141) theQoS information corresponding to the parameters, the ASS forwarding theQoS information to the ASC 118).
 28. ASS (113) according to any of theclaims 23-27 wherein the ASS (113) is further adapted for subscribing tochanges in QoS information from the PCRF (111).
 29. ASS according toclaim 28 wherein the ASS (113) is further adapted for, when receivingQoS information changes from the PCRF (111) as a result of thesubscription to changes in the QoS information, further informs the ASC(118) of these QoS information changes.
 30. Access Selection Client(ASC) (118) being arranged in a communication network comprising atleast one User Equipment (UE) (109) and communication nodes, accessselection information being used in the network for the selection ofnetwork access for the UE (109) in a multi-access environment to aPacket Data Network Gateway (PDN GW), the network access enabling atraffic bearer (116) between the UE and the PDN GW for the traffic flowbetween an application (AP) (115) in the UE (109) via the PDN GW to afirst node, characterized in that an Access Selection Client (ASC) (118)being arranged in the UE (109) is adapted for performing (129,143)activation of new network accesses and/or selection, modification ordeactivation of existing network accesses on the basis of the accessselection information in order to enable the traffic flow (116), theselection/activation/modification/deactivation (143,144) of the networkaccess being triggered by a socket request sent (137) from theapplication (AP) (115) to the ASC (118) for the purpose of establishingmeans for end-to-end communication including the traffic bearer (116).31. ASC (118) according to claim 30 wherein the ASC is further adaptedfor receiving (136) information about a network access selected togetherwith QoS information and/or TFT parameters.
 32. ASC (118) according toany of the claims 30-31 wherein the ASC is further adapted for sending(138) a request including the socket parameters to an Access SelectionServer (ASS) (113), requesting the ASS (113) to send back (142) the QoSinformation corresponding to the sent traffic flow socket parameters.33. ASC (118) according to any of the claims 30-32 wherein the ASC (118)is further adapted for performing a default network access decision whenthe socket request is received.
 34. ASC (118) according to any of theclaims 30-33 wherein the ASC (118) is further adapted for performing(143) the selection/activation/modification/deactivation of a networkaccesses on the basis of the QoS information received (142) by the UE.35. ASC according to any of the claims 30-34 wherein the ASC (118) isfurther adapted for performing a handover between two different networkaccesses as a part/result of theselection/activation/modification/deactivation.
 36. ASC according to anyof the claims 30-35 wherein the ASC (118) is further adapted for storingthe received (136,142) QoS information.
 37. System for network accessselection, comprising an Access Selection Server (ASS) (113) beingarranged in a communication network comprising at least one UserEquipment (UE) (109) and communication nodes, the ASS (113) beingadapted for collecting (127,141) access selection information used inthe network for the selection of network access for the UE (109) in amulti-access environment to a Packet Data Network Gateway (PDN GW), thenetwork access enabling a traffic bearer (116) between the UE and thePDN GW for the traffic flow between an application (AP) (115) in the UE(109) via the PDN GW to a first node, characterized in that an AccessSelection Client (ASC) (118) being arranged in the UE (109) is adaptedfor performing (129,143) activation of new network accesses and/orselection, modification or deactivation of existing network accesses onthe basis of the access selection information in order to enable thetraffic flow (116), the selection/activation/modification/deactivation(143,144) of the network access being triggered by a socket request sent(137) from the application (AP) to the ASC (118) for the purpose ofestablishing means for end-to-end communication including the trafficbearer (116).
 38. System according to claim 37 wherein the ASS (113)further being adapted for sending (128,136,142) the access selectioninformation to the UE (109).